Venezuela's Communication Minister Jorge Rodriguez said a plane that had come from the United States flew over the Caracas airport "flight information region," without explaining its reasons for doing so.

On Sunday, US defense officials said a Russian-made Venezuelan SU-30 had followed a US EP-3 aircraft at an "unsafe distance ... jeopardizing the crew and aircraft."

The US Southern Command (SOUTHCOM) blasted the maneuver as "unprofessional" and claimed the EP-3 was "flying a mission in approved international airspace."

It also claimed the action demonstrated Russia's "irresponsible military support" to Venezuelan President Nicolas Maduro's "illegitimate regime."

Maduro's right-hand man, Diosdado Cabello, alluded to the two incidents in a press conference on Monday, hitting out at the "very serious military actions" by the US military that he said were "threatening" Venezuela.

"All threats will elicit an immediate response" from the Venezuelan military, he said.

Venezuela and the United States have been at loggerheads since Maduro's predecessor, the late Hugo Chavez came to power in 1999.

Chavez aligned himself with communist Cuba under the late Fidel Castro and other socialist regimes in Latin America, and was a prominent critic of Washington.

Venezuela has been in political crisis since January, when opposition leader Juan Guaido declared himself acting president in a direct challenge to Maduro's authority.

The United States was one of the first of more than 50 countries to recognize him as such.

Venezuela's opposition say Maduro is a "usurper" and claim he was re-elected last year in a rigged poll.